Hydrolytic decomposition product of the epidermis of hogs, etc.



Patented July 4, 1939 UNITED STATES PATENT OFFICE HYDROLYTIGDECOMPOSITION PRODUCT OF THE EPID'ERMIS' F HOGS, ETC.

Charles H. CampbelL'Kent, Ohio 2 Claims.

This invention relates to products obtained by the hydrolyticdecomposition of the epidermis of hogs and such foreign matter as may bepresent after removal and separation of the hair or bristles from saidepidermis. This application is a division of my application Ser. No.211,044, filed May 3, 1938.

The derivatives or cleavage products resulting from my invention providean excellent reinforcing agent or filler for rubber possessing noproperties harmful to rubber over a long period of time. Moreparticularly this reinforcing agent or filler is capable of making therubber soft, tacky and dead in character before vulcanizing thoughresilient, elastic and tough with an excellent grain when vulcanized.

The derivatives or cleavage products produced in accordance with myinvention are those obtained by the hydrolytic decomposition of theepidermis of hogs to the point of obtaining soluble and diffusiblecleavage products but preferably short of such hydrolytic decompositionas will form amino-acids, though some may be present, and preferablyalso those soluble and diffusable cleavage products obtained by thehydrolytic decomposition of the epidermis of hogs through the influenceof heat and pressure by steam.

In this country, the slaughtering and subsequent treatment of hogs isusually carried out in a manner that permits recovery of the epidermis,and prior to my invention the epidermis was disposed of as waste whichhad no known value of any consequence. After killing, the hogs aresubjected to a scalding treatment which loosens the epidermis from theunder skin and then they are scraped. This scraping removes theepidermis and dehairs the animals, providing a mixture of epidermis,hair and bristles which is cleansed or washed with a suitable agent andthe hair and bristles separated from the epidermis, the latter beingthrown away as waste. The foregoing treatment of hogs is well understoodin the art.

The epidermis remaining after the separation of hair and bristles, afterbeing subjected to further treatment that will be referred to, isthematerial I use to produce my product. While there may be some impuritiesin this material, such as very short hairs which are unavoidablyretained, a little blood albumen, and possibly a small amount of saltswhich are usually found in the epidermis of any animal, the materialconstitutes largely the epidermis and is to be so considered herein.

I take the recovered epidermis and place it in a closed digester tohydrolyze and decompose it. Hydrolytic decomposition is effected byadmitting steam to the digester and in some instances a small amount ofcaustic soda may be added. Steam admitted at 100 lbs. pressure forapproxi- 5 mately two hours has been found to be ample in connectionwith the epidermis obtained from young animals. With the olderepidermis, however, it is desirable to carry on the digesting processfor a longer period of time as for example even up to six hours. Theprocess can be hastened, however, by increasing the steam pressure orsuperheating the steam. The difficulty with the higher steam pressures,however, especially when epidermis of a miscellaneous type is beingtreated 10 in large quantities at one time, such as 15,000 to 20,000pounds or more, is that the higher steam pressures when long continuedare apt to have a too drastic action on the epidermis and produce anundue proportion of the amino-acids. Accordingly it is desirable toraise the steam pressure gradually and to remove the soluble cleavageproducts at intervals rather than make one long digestion to prevent thefirst fraction of cleavage products formed, from hydrolyzing throughinto 93 the amino-acid group although at times some may be present. Thussteam might first be admitted to the digester at about 60 poundspressure for about two hours, the steam then shut off, pressure on thedigester relieved and the soluble products thus far formed removed.Steam might then be admitted at 80 pounds pressure for a further periodof two hours, the steam then shut 01f, the pressure relieved and thesoluble products again removed. Steam may then well be admitted to thedigester at 100 pounds pressure for a period of at least two hoursdepending upon the condition of the mass within the digester. Theresulting material is a flowable liquid, usually of a dark color, inwhich the epidermis has been fully dissolved.

At the expiration of the hydrolyzing process the liquid material ispassed to a suitable dryer wherein all except about 2% to 3% of themoisture content is preferably removed. Any commonly accepted dryingprocess may be used and I prefer to use either an open pan or a stickroll in drying. This gives us a dried, solid material which is nextground up into a fine powder, which should be immediately bagged inmoistureproof bags to prevent caking.

The epidermis derivatives thus obtained constitute a very satisfactoryreinforcing agent or filler for rubber which is mixed or compoundedpreferably in its powdered form with the rubber,

before vulcanizing in the ordinary manner. In compounding reclaims thepowder is preferably added after the rubber leaves the dryer, the rubberusually having enough moisture content to permit dispersion of thepowder through the rubber. With natural rubber it is desirable, thoughnot necessarily essential, to make up a master batch with my powder init and then use the desired percentage of the master batch withadditional rubber.

The epidermis is an albuminous protein distinctly different in characterand makeup from keratin, collagen or e1astin,which are also animalproteins. With the latter animal proteins it usually requires from 3% to6% thereof by weight added to rubber in order to produce the desiredresult, whereas, with the present material as little as 2% by weight canbe satisfactorily used, producing a result which, according to testsmade, is as high as 20% better than has heretofore been possible withother materials, this increase being noticeable in both the compoundedproduct and the finished product.

Among the reasons why rubber compounded with epidermis is moresatisfactory is that epidermis does not appear to be detrimentallyaffected by the high temperatures used in treating rubber. The finishedrubber product is resilient and. pliable, is capable of a very largenumber of flexing actions without cracking, is tough, and is not subjectto the deterioration that sometimes takes place when other animalproducts are compounded with rubber.

It will be apparent that modifications of the invention may be resortedto without departing from the spirit thereof or from the scope of thesubjoined. claims.

What is claimed is:

1. A new product of manufacture comprising the hydrolytic decompositionproducts of the epidermis of hogs and such foreign matter as may bepresent after removal and separation of the hair or bristles from saidepidermis, and which products are substantially short of amino-acids.

2. A new product of manufacture comprising soluble and diffusiblehydrolytic decomposition products of the epidermis of hogs and suchforeign matter as may be present after removal and separation of thehair or bristles from said epidermis, and which products aresubstantially short of amino-acids.

CHARLES H. CAMPBELL.

